Casey's USPGA injury worry

GOLF: England&rsquo;s Paul Casey is a major doubt for next week&rsquo;s US PGA Championship after suffering a chest injury last night.<br /> The world No3 pulled a muscle teeing off at the seventh hole of the WGC Bridgestone Invitational in Ohio.<br /> <br /> Three-time major winner Padraig Harrington held the early clubhouse lead with a six-under-par 64.